When forming packaging containers made of packaging material such as laminate, there are at least two general techniques to follow. According to one technique each package is formed from an individual blank severed from a web of packaging material, which is formed into an individual packaging container, which in turn is filled with product. According to a second technique the web of material is longitudinally sealed to form a tube, and during sealing the tube is filled with product and then transversally sealed and severed to form individual containers. The present invention relates to the second technique. The skilled person realizes that the above description merely represents a rough classification and not an exhaustive list. To elucidate the relevant area further there are numerous different types of prior art apparatuses and arrangements for sealing packages once they have been filled with food and/or beverage products in filling machines. The packages are often manufactured from a tube of packaging material which is conveyed through a filling machine. The packaging material may consist of one or more layers of material depending upon the type of product which is to be filled in the packages. Certain packages are manufactured, for example, from a layer of plastic which is sealable by means of melting heat, occasionally a plurality of plastic layers, while other packages consist, for example, of a plurality of different material layers, such as a fibrous material, e.g. paper, which is coated on both sides with layers of meltable or fusible plastic, for example polyethylene, and may also include an additional material layer, for example of aluminium, which functions, as a barrier in aseptic packages.
The tube is conveyed in a per se known manner through the filling machine at the same time as it is filled the product, sealed and given its final configuration. The individual packages are sealed in that two sealing jaws which are displaced towards one another grip and compress the tube in transverse zones uniformly distributed along the length of the tube. The jaws consist of a counter jaw and a jaw for generating heat, for example a so-called ultrasound horn which generates the heat by means of ultrasound. The heat may also be generated in other ways, for example by means of constant heat or induction, for sealing of each respective compressed tube section by melting associated plastic material and thereafter severing each respective tube section so that individual packaging containers are obtained. Thereafter each packaging container is folded into the desired shape, which often is assisted by prearranged creasing lines in the packaging material. One example of the above is disclosed in WO2006073339.
In some instances the sealed and folded packaging container exhibits unacceptable production errors resulting from an imperfect sealing and folding process. These errors, such as dents, may be an aesthetic problem only, yet it may also result in defective seals, which in turn results in a discarded packaging container (and product contained therein). Further, dents may result in an increased risk of leakage during transportation of packaging containers, which may jeopardize the quality of packaging containers stored in the vicinity leaking one. Errors during the folding process may also result in poor standing stability for the finalized packaging container.